Examples of conventionally known methods of removing toxins or biologically hazardous organisms, such as viruses or pathogenic bacteria, from blood, a blood derivative or other similar matter in which such hazardous substances are contained include methods that call for heating organisms or toxins so as to kill, decompose or otherwise inactivate them, methods that call for mixing a photoactive pigment into the matter containing such a substance and inactivating the substance by irradiation with light, methods that call for inactivating hazardous substances by electrolysis, and methods that call for physically separating and removing hazardous substances with a filter.
However, methods that call for inactivating viruses, pathogenic bacteria or toxins by heat treatment present a problem in that the heat causes denaturation of not only the viruses, the pathogenic bacteria or the toxins but also constitutive proteins that constitute the blood or the blood derivative, and that complete inactivation of viruses, pathogenic bacteria or toxins inevitably requires heating conditions that are harsh to constitutive proteins. Methods that call for physical separation and removal of hazardous substances with a filter are often incapable of complete removal of viruses, pathogenic bacteria or toxins. As with methods using heat treatment, methods that call for electrolysis to inactivate viruses, pathogenic bacteria or toxins present the possibility of denaturation or decomposition of constitutive proteins together with the viruses, the pathogenic bacteria or the toxins and require harsher heating conditions to constitutive proteins to completely inactivate the viruses, the pathogenic bacteria or the toxins. These drawbacks of the individual methods have resulted in the present situation where a combination of different methods, for example heat treatment and separation removal using a filter, is usually employed, although the treatment process is complicated and time consuming.
Methods that call for mixing a photoactive pigment into blood and inactivating hazardous substances by irradiation with light involves mixing a pigment into blood or a blood derivative, which will enter a human body or the like. Therefore, it is necessary to choose a highly safe pigment that does not cause rejection symptoms. However, this results in various problems, including such complications as selecting pigments and confirming the safety of the pigments, limitations in usable pigments, and the limited range of use.
At present, when performing a clinical examination of drawn blood or body fluid, the blood or the body fluid itself does not undergo sterilization regardless of whether the subject is infected with any disease, because conventional sterilization for removing viruses or bacteria typically uses a chlorine-type disinfectant, an alkaline disinfectant or heat treatment and causes denaturation of components of the blood or the body fluid. In other words, conventional sterilization is effective when disposing such fluids but not suitable for preliminary treatment performed prior to a clinical examination. Therefore, when a clinical examination is conducted, sterilization treatment is not performed on the sample itself but only for protecting the handler of the sample from infectious diseases, i.e. what is generally called prevention of biohazard.
A semiconductor has the property of being energized, i.e. the state where electrons and pairs of holes are formed inside the semiconductor when irradiated with light having energy exceeding the band gap, i.e. the width of the forbidden band, of the material that constitutes the semiconductor. For example, titanium dioxide is energized by irradiation with long-wave ultraviolet or visible light and exhibits slight reduction capability and great oxidizing ability. As titanium dioxide is inorganic, it is completely harmless to the human body when it is not in the energized state. Because of this feature, titanium dioxide is used as an antiviral or antibacterial substance by using its great oxidizing ability, as is shown in, for example, Japanese Patent Provisional Publication Nos. 1994-254139, 1996-23970 and 2000-41667.
The conventional art disclosed in Japanese Patent Provisional Publication No. 1994-254139 calls for forming by thermal spraying a layer of composite ceramic on the surface of a base member to be exposed to a gas or a liquid, said composite ceramic consisting of a photo-semiconductor ceramic, such as titanium dioxide, and a ceramic having the adsorption capability, such as apatite. The base member is then brought into contact with a liquid or a gas so as to cause the ceramic having the adsorption capability to adsorb viruses and/or bacteria contained in the liquid or the gas, and light is radiated to the composite ceramic to inactivate the adsorbed viruses and/or bacteria.
The conventional art disclosed in Japanese Patent Provisional Publication No. 1994-254139, however, is not capable of effectively inactivating just bacteria or viruses, because there is the possibility of the ceramic having the adsorption capability also adsorbing components of the gas or the liquid, thereby undesirably causing denaturation or decomposition of the constitutive components.
The art disclosed in Japanese Patent Provisional Publication No. 1996-23970 calls for suspension dispersion of fine-grain photocatalyst made of titanium dioxide or other appropriate matter in a body fluid, such as blood, and inactivating viruses in the body fluid by irradiation with light.
However, the treatment process according to the method disclosed in Japanese Patent Provisional Publication No. 1996-23970 is complicated in that it requires a process of separating the titanium dioxide from the liquid. Furthermore, the method is not capable of effectively inactivating just viruses, because the strong oxidization capability of the titanium dioxide causes denaturation or decomposition of the constitutive components of the liquid, such as blood.
The art disclosed in Japanese Patent Provisional Publication No. 2000-41667 calls for supporting a photocatalyst made of, for example, titanium dioxide on the surface of a substance which will be exposed to blood or a blood derivative, and irradiating the photocatalyst with light so as to reduce through inactivation the infectivity of the viruses or the bacteria that have entered the blood or the blood derivative.
However, the method disclosed in Japanese Patent Provisional Publication No. 1996-23970, too, is incapable of effectively inactivating just infectious substances, such as viruses or bacteria, because the strong oxidization capability of the titanium dioxide causes denaturation or decomposition of the constitutive proteins in the blood or the blood derivative.
In other words, as is true in those disclosed in Japanese Patent Provisional Publication Nos. 1994-254139, 1996-23970 and 2000-41667, a method that calls for inactivating bacteria or viruses by using titanium dioxide, which shows the strong oxidization capability when irradiated with light, is incapable of effective treatment in that it denatures or decomposes not only substances to be inactivated, such as bacteria or viruses, but also constitutive components of the sample.
In order to solve the above problem, an object of the present invention is to provide a treatment agent, a method and a device for treating specific hazardous substances, such as viruses, bacteria or toxins by efficiently inactivating such hazardous substances.